Device for recording pulse waves, respiration, and blood pressure changes



March 25, 1941. c. D. LEE 2,235,894

DEVICE FOR RECORDING IULSE WAVES, RESPIRATION, AND BLOOD PRESSURE CHANGES IN V EN TOR.

ATTORNEYS.

March 25, 1941. C D LEE 2,235,894

DEVICE FUR RECORDIN P'ULSE WAVES, RESPIRATION, AND BLGOD PRESSURE CHANGES Filed Jan. 18. 1958 3 Sheets-Sheet 2 y', 'l l/ l I' Il' IN VEN TOR. @MEE/VCE L ATTORNEYS.

March 25, 1941 2,235,894

C. D. LEE DEVICE FOR RECORDING PULSE WAVES, RESPIRATIOI, I

AND BLGD PRESSURE CHANGES Filed Jan. 18, 1938 3 Sheets sheet 5 INVENTOR. @ggf/Va@ f ATToRNEYs.

Patented Mar. 25, 1941 UNITED STATES PATENT OFFICE nevica ron. RECORDING PULSE waves,

RESPIBATION, CHANGES AND BLOOD PRESSURE My invention relates to improvements 1n a device for recording pulse waves, respiration and blood pressure changes, and it consists oi the combinations, constructions and arrangements hereinafter described and claimed.

An object of my invention is to provide a device for recording pulse waves, respiration and blood pressure changes. which will make a graphical record oi the pulse waves, blood pressurevariations, and the respiration in the human body. The device can also be used in clinical work for the study of the circulation of the blood. 'I'he drawings illustrate the device when used as a psychograph (lie detector). The device makes use of a cardiograph for making a record of the pulse waves of the person being examined. A pneumograph is also used with the device and this will make a record of the individuals respiration. In addition to these two units, a signal device is employed for making marks on the chart at any desired point. The cardiograph, the pneumograph, and the signal device, all operate pens that move over a graph chart which in turn is moved at a predetermined speed by any desired mechanism such as by a synchronous motor.

The cardlograph and pneumograph units are novel in construction and are so designed that they will move the pens over the chart without any outside power being necessary other than that obtained from the pulse and the breathing of the individual being examined. The entire device is also made so simple as to be readily disassembled and assembled without the need of any tools. This permits the diaphragms used in the various units to be quickly changed.

ther objects and advantages will appear in the following speciiication, and the novel features of the device will be particularly pointed out in the appended claims.

My invention is illustrated in the accompanying drawings forming a part of this application, in which Figure 1 is a top plan view of a. portion of the device;

Figure 2 is a section substantially along the line 2 2 of Figure 1 and shows the chart drive diagrammatically;

Figure 3 is a section substantially along the line 3-3 of Figure 2 and shows the various parts used in connection with the cardiograph, pneumograph and signal device;

Figure 4 is a section substantially along the line 6-4 of Figure 2;

Figure 5 is a section along the line 5-5 on Figure 6;

Figure 6 is a section along the line S-S on Figure 5;

Figure 7 is a section along the line 1--1 on Figure 6; and

Figure 8 is a front elevation of the compres- 5 sion ring.

In carrying out my invention, I provide a casting indicated generally at I, in which I mount a cardiograph unit indicated generally at A, in Figure 3, and a pneumograph unit indicated generally at B. Figures l and 2 show a chart drive mechanism indicated generally at C associated with the cardiograph and pneumograph units.

In actual practice, the casting i containing the units A and B, will be placed in a box (not shown) 15 and the chart drive C will be placed alongside the casting. The bex will be made large enough to provide a space for receiving a pump bulb D, see Figure 3, a pressure bag E, for the arm, and a receptor F, for the chest. A signal device G is 2G also receivable in the space. All of these parts will be explained more in detail hereinafter. The box is provided with a cover and when the cover closed, all of the parts will be concealed so that the entire device may be readily carried. 25

I will describe the cardiograph. then the chart drive, the pneumograph, the signal device, and a shut on' valve H, in the order named.

Cardiograph 3G The casting i has a panel 2 which is preferably made of Bakelite, see Figure 2. The casting has its bottom wall 3, spaced above a supporting s 1- face i which constitutes the bottom oi the bon, not shown. The bottom 3 is supported by legs 5 35 that extend transversely across the two ends of the casting. The casting is also provided with a rear wall E and front corner posts l. it will also be seen from Figures 2 and 4 that a bar 8 extends across the front of the casting and is disposed near the bottom wall 3.

The cardiograph A is shown in section in Figures 2 and 3 and it comprises a cylinder 9 placed between a top plate l0 and a bottom plate li. Rubber diaphragms l2 and i3 are placed between 45 the plates and the cylinder, and the cylinder hermetically seals the diaphragms to the plates when the plates are secured to the cylinder by bolts i4 and wing nuts l5. Figure 3 shows four bolts I4 being used. The lower plate ll has legs 50 Il' for supporting it above the bottom wall 3. Screws l' hold the legs to the bottom wall.

The plates l0 and Il have dome-shaped recesses I6 and il respectively, and pipes I8 and I9 communicate with these recesses. I will de- 55 scribe hereinafter how air, under pressure, is forced into the pipes i8 and Il for expanding the diaphragms I2 and Il into the semispherical shape shown in Figure 2. The air connned within the diaphragms and their associated plates is at a higher pressure than that conined in the portion of the cylinder disposed between the two diaphragms. In other words. the cylinder will contain two high pressure regions and one low pressure region. It will further be noted that as the diaphragms are expanded by the air pressure, they will first contact with each other at the center of the cylinder, and yet the diaphragms will be sensitive to variations in pulse beat pressures in a manner hereinafter described.

Ihe pressure chamber containing the high and low pressure regions has a tambour I, connected therewith. Figures 2 and 3 show the cylinder 9 as being provided with an air passage 20 that communicates with an air chamber 2i. A membrane or diaphragm 22 is stretched across the open end of the chamber 2i and is connected to a removable plate 23 by bolts 24. The bolts are passed through openings in the diaphragm 22 and are also passed through aligned openings in the plate 23 and in a ange 25. Nuts 26 are mounted on the bolts 24 and when tightened by hand, will cause the cylinder wall 2l of the air chamber 2i to hermetically seal the membrane 22. Figure 3 shows a pipe 2t eirtending through the cylinder wall 9, and this pipe may be closed by a means hereinafter described and will trap air in the low pressure region. It will therefore, be seen that variations in the air pressure in the high pressure regions will vary the pressure in the low pressure region and this will cause the membrane 22 to hex in accordance with these air pressure changes.

In order to stretch the membrane 22 to the desired extent, I provide a tension ring This ring is threaded into a threaded opening in the plate 23 and it may be rotated for pressing against the membrane 22 to the desired extent. The ring is marked with the numbers 0, l. 2, and 3, see Figures 4 and 8, and the number 0 will register with an arrow 3d marked on the plate 23 when the inner edge of the ring is ush with the inner surface of the plate. A quarter turn of the Aring in a clockwise direction, when looking at Figures e and 6, will bring the number 1 into registration with the arrow 3b. The ring will be moved inwardly by this rotation and will stretch the diaphragm 22. The rotation of the tension ring is continued in the same direction until the diaphragm 22 offers a slight resistance. Usually a half or three-quarter turn of .the ring will give the desired tension to the diaphragm 22.

The diaphragm 22 is connected to a pen mechanism, indicated generally at Si in Figure 2 in the following manner. A link 32- see Figures 3, 5, 6 and 7, has a spherical head 33, received in a socket 3d and this socket is held against the diaphragm 22 by a rubber disc 35 that covers the socket and is cemented to the diaphra 22. The rubber disc has an opening through which the link extends. The free end of the link is provided with a plurality of openings 36 and a sliding spring lever arm 3l, see Figures 4, 5, 6 and 7, is pivotally mounted in the desired opening 36. The lever arm Si is in the nature of a spring and slidably received in openings 3B formed in a pen shaft 39. The spring action of the arm frictionally engages with the sides of the openings Il and it therefore will be held in the position in which it is moved. In this way the amount o rocking imparted to the pen shaft 39 may be varied at will.

Figure 4 also shows the pen shaft 39 mounted in an adustable bearing 40 carried by the cross bar I. Figure 4 also shows the pen shaft extending through an opening 4| in the panel 2.

Abearing bar 42 is secured to the panel by screws 43 and rotatably receives the top of the penshaft 39. Figure 2 shows the shaft 39 carrying a pen holder 44 and this pen holder is adjustably secured in place by a set screw 45. The pen holder carries a spring socket 46 that receives the inner end of a pen arm 41. The outer end of the pen arm carries a pen point 48 which is in the form of a cylinder with a conical bottom provided with a small orifice through which the ink carried in the cylinder will gradually now. The arm 41 may be raised or lowered vertically by a set crew 49. In this way the proper amount of pressure may be applied on the arm for causing the ink to flow onto the chart.

Chart drive The chart drive is shown diagrammatically in Figure 2. A chart 50 is fed from a roll indicated generally at 5i and is passed around an idler roll 52. The chart is then moved between guides 53 and over sprocket wheels 56. The sprocket wheels are mounted on a common shaft 55 and this shaft carries a gear 5t. The gear 5 is operatively connected to a motor driven gear 5l by an intermediate gear 58. The gearing is such as to cause the chart 5o to move at a predetermined speed. The motor 59 is preferably of a synchronous type so that the gear 5l will rotate at a certain speed and thus cause the chart to move a predetermined distance in a deiinite time period. In Figure 1, I show the chart d@ as being marked oii by lines et, and these lines indicate intervals of time. When the device is placed in the box, not shown, one end of the box is preferably provided with a slot through which the chart will feed.

A panel knob 6i is shown in Figures 1 and 2 and this knob is connected to a shaft t2 that operates a switch indicated generally at b3. The switch when closed, electrically connects the synchronous motor 5S, with a source of current, not shown. The panel 2 has the word Motor stamped thereon, at a place adjacent to the knob el. The words OE and 0n are also stamped on the panel in proper positions with respect to the knob. A pointer Gli is carried by the knob and when the switch is open, the pointer will be directed to the OE position. A turning of the knob in a clockwise direction will swing the pointer @d to the word On. This movement will close the switch and the self-starting synchronous motor 5@ will immediately operate to feed the chart 5@ beneath lthe pen 48 at a predetermined speed. It is obvious that any other type of chart-movingmechanism may be employed Without departing from the spirit and scope of my invention.

Pneumograph As already stated the pneumograph is shown at B, in Figures 3 and e. The pneumograph consists of a tambour that is identical to the tambour I, except that the plate 65, diers from the hanged member 25, in that it does not communicate with a low pressure region in a cylinder corresponding to the cylinder 3. Since al1 ci the other parts of the pneumograph are identical to the tambour I, corresponding parts will be given like reference numerals, except that these numerals will be primed. The plate Il supports an outlet pipe 66 communicating with the air chamber 2i. The pipe 6I has a branch i1 to which a flexible tube 69 is connected.

The tube 64 extends through an opening 99 in the rear wall l of the casting I and ls connected to the pick-up or receptor F, see Figure 3. The receptor F is of a standard construction and consists cf a thin-walled rubber tubing 19 that is placed over a coil spring 1I. The tube Il communicates with the tubing 10. An adjustable strap 12 is connected to the ends of the tubing 1B and is designed to pass around the back of the person to be examined and to hold the tube 10 across the chest. The strap 12 is tightened to hold the tube 10 in place, and the normal breathing of the person will cause the tubing 10 to be lengthened and shortened directly in accordance with the breathing of th e person. This will alter the capacity of the tubing 1li and will cause pulsations of air to flow through the tube 68.

These pulsations will flex the diaphragm 22' and the diaphragm in turn will cause the link 32 to swing the shaft lever arm 31', which in turn will rock the pen shaft 39' about its vertical axis. Figure 4 shows the shaft 39' extending through an opening 4|' in the panel 2 and as being journalled in the bearing bar 42. The top of the pen shaft 39' carries the pen holder 44' and Figure 1 shqws the pen holder as carrying a pen arm 41', which supports a pen 48' at its free end. The pen 48' is moved laterally and will make a graph on the chart 50 in direct accordance with the respiration of the individual being examined. The purpose of the pipe 66 will be described hereinafter. The front plate 23' extends down to the floor 3 of the casting and screws 3" secure it in place, see Figure 4.

Signal device The signal device is shown in Figures 1, 3, and 4. The device operates a pen mechanism identical to the pen shaft 39, pen holder 44 and the pen 48. Since these parts are identical, corresponding reference numerals will be given, except that they will be double primed. The shaft 39", see Figure 4, is shown centrally disposed between the shafts 39 and 39'. Any mechanism for rocking this shaft on its vertical axis will suffice and I have illustrated one such mechanism as comprising an arm 13, see Figure 1, connected to the shaft 39 by a collar 13'. The free end of the arm 13 may be connected to the inner end of a flexible plunger shaft 14, see Figure 1. by any means desired. such as by a pin 15 sliding in a slot 16 formed in the free end of the arm 13. The inner end of the plunger shaft 14 may be supported by a collar 11 and this collar freely slides on a rod 18 that in turn is supported by the casting i. A coil spring 19 is mounted on the rod 18 and returns the collar 11 to normal position which will bring the pen 48" back into a zero reading.

The flexible plunger shaft 14 extends through a flexible cable supported by the rear wall 6, and this cable, see Figure 3, leads to a casing 8| that has wings 62 for receiving two fingers of the hand. The flexible plunger shaft 14 extends through the casing 8i and is provided with a head 83 that may be depressed by the means of the thumb. If desired, the casing Il may contain a spring, not shown, for returning the head 93 to normal position after it has been depressed by the thumb. In this event the spring 19 may be dispensed with. Any other means for moving the pen 44" may also be used.

It will be seen from this construction that each time the head 93 is manually depressed, the ilexible shaft 14 will be actuated for swinging the arm 13 and rocking the shaft 39" for moving the pen 4l". Since the pen 4l" is filled with ink, it will make a transverse mark on the chart 5l. The head 43 may be depressed as often as desired and when the device is used as a lie detector, the head is pressed each time a question is asked the individual being examined.

Shut-o17 valve This valve is shown in Figures 2 and 3 and it comprises a casing I4 that is carried by the rear wall i of the casting I. 'I'his casing has three sets of aligned openings 35, 46 and l1 in its side walls, and these openings are disposed near the top of the casing. A clamping member I3 is disposed in the casing 34 and Figure 2 shows the top surface of this member as being semi-cylindrical. The member extends throughout the length of the casing and it may be raised and lowered by means of a screw shaft I9. 'Ihis shaft is threaded into the clamping member and extends through an opening SI in the panel 2. A knob 9| is mounted on the shaft 39 and a turning of this knob will rotate the shaft for raising the clamping member I8 toward the top of the casing 84.

Figure 1 shows the panel 2 provided with the word Pens adjacent to the knob 3l. The words Off and On are also associated with the same knob and a pointer 92 is carried by the knob and points to the word Off when the clamping member 88 is disposed at the bottom of the casing 34. When the knob is rotated so that the pointer 92 will indicate the "On" position, the screw shaft 89 will raise the clamping member to a position near the top of the casing.

Figure 3 shows three rubber tubes 93, 94 and 95, extending through the aligned openings 85, 8i and 81, respectively. The tube 93 connects with the pump bulb D and with a header 91. In order to avoid confusion, a portion of the tube 93 extending from the casing 84 to the header 91, is shown diagrammatically by a single line. Portions of other tubes are shown in like manner. An air leak valve of standard construction is shown at 98 and is disposed between the pump bulb D and the tube 93. The tube 94 extends to the pipe 28 that communicates with the low pressure chamber in the cylinder 9. The tube 95 extends to the pipe 66 and communicates with the air chamber 2i. The tubes 94 and 95 terminate adjacent to the rear wall 8, and open to the atmosphere. When the knob 9i is turned into the On position, the clamping member 83 Will be raised and will squeeze ail of the tubes 83, 94 and 95 shut, and make an air-tight seal for these tubes during the operation of the dcvice.

Before describing the operation of the device lt is best to state that the other four outlets of the header 91 are connected to different parts of the device by rubber tubing. The outlet Sla is connected to the pipe i9 of the high pressure area in the cylinder 9 by a tube 81', While the outlet 91h is connected by a tube, not shown, to the pipe i8 communicating with the upper high pressure area in the cylinder 9. The outlet @lo is connected by a tube, not shown, to a blood pressure gage Q9 shown in Figure l. The rubber tube that extends from the outlet tlc, communicates with a stub pipe IW that leads to the operating mechanism in the gage 99. The gage is preferably calibrated in centimeters and indicates the blood pressure in the body.

The outlet 91d of the header, has a rubber tube lill connected therewith and extending through an opening |02 in the rear wall 6 of the casting l. This rubber tube connects with the pickup E of standard construction. The pick-up E consists of a sleeve |03 designed to encircle the arm of the individual and the sleeve contains a ilexible rubber compartment |05 that receives air under pressure by means of the tube lili. 'Ihe pressure of the air pumped into the bag loll is indicated by the blood pressure gage 9d.

Operation From the foregoing description of the various parts of the device, the operation thereof may be readily understood. l

The receptor Fis strapped in place so that the tubing Will extend across the chest. While this is being done the knobs 6| and 9| remain in the Oi position and therefore the manipulation of the tube 10, will not cause the pen 48 to move. The knob 9| when in 01T position will open the tube 95 and this will place the air chamber 2l in communication with the atmosphere. It is for this reason that any changes in the air capacity of the tube lll, while being placed in position on the chest, will not flex the diaphragm 22 and will not cause the pen 68 to move.

The pressure bag E is now placed over the arm of the person. The rubber compartment ii of the pressure bag is now via tube @5 inated by actuating the inating bulb D. A thumb nut @du on the air-leak valve @t is rotated into closed position during the actuation of the pump bulb D. The bulb D will therefore force air through the tubing s3, the header di and out through the outlets 97a and 9% to the pipes i6 and i9 where the air will enter the high pressure regions in the cylinder 9 and innate the diaphragms l2 and i3. At the same time air will be delivered through the header outlets No and 97d to the pressure gage 99 and to the rubber bag ltd. When the desired amount of air pressure is reached, as shown by the gage 99, the panel knob 9| is turned from the Off" position into the On position. 'Ihis will lift the member 9S and close the tubes 93, SB and 95. During the iniiation of the diaphragms l2 and i3, the pen d8 also remains at aero reading because the low pressure region in the air chamber 2| communicates with the atmosphere through the tubing 94. Any exing of the diaphragms E2 and i3 caused by the pulse of the individual being examined, will have no eiect upon the diaphragm 22, until the tubing @d is closed. The device is now ready to actually record the respiration and the pulse beat of the individual.

The panel knob 6| is now turned into the On" position and this closes the electric circuit to the self-starting synchronous motor 5S. The chart 50 will therefore move at a given rate of speed so that the lines 60 will indicate denite time periods. The pulse beat of the individual will vary the capacity of the bag iil and this in turn will cause pulse waves to ow through the tubing |U| header 97|, to the pipes I8 and i9 by means of the tubing El and the tubing, not shown, connecting the outlet Sib to the pipe it. The pulse of the individual will therefore cause the diaphragme. i2 and t3 to ex in direct proportion to the pulse beat, and this flexing of the diaphragms will alter the capacity of the low pressure region. Since the low pressure region in the cylinder 9 has been cut off from communication with the atmosphere by the 'closing of the tube 94, the variations in the capacity of the low pressure region will cause the diaphragm 22 to flex in direct ratio with the diaphragms i? and I3. It will therefore be seen that the diaphragm 22 will be iexed in direct ratio to the pulse waves of the individual.

'Ihe exing of the diaphragm 22 will reciprocate the link 36 and by means oi the arm 3l will rock the pen shaft 8d. This movement will swing the pen arm 4l and will cause the pen 88 to make a graph on the moving chart 50 in direct accordance to the pulse wave of the individual.

At the same time the normal breathing of the person will change the capacity of the rubber tubing l and this will cause a variation of air pressure in this tubing and in the tubing 68. A Wave will be transmitted by the pipe 68 to the air compartment 2|' with the result that the diaphragm 22 will be flexed in direct ratio with the respiration of the individual. The flexing of the diaphragm 22' will cause the pen 48' to swing laterally and to draw a graph on the chart Sil. The graph will show the respiration of the individual.

When the device is used as a psychograph, the operator at the time of asking a question, presses the plunger 83 and this will cause the pen d8 to make a mark on the chart in the manner already described. Should the person being examined lie, when answering the question, the pulse beat will increase and so will also the blood pressure. This will cause the pen it to move more rapidly and also to swing to a higher position on the chart 5t. At the same time, the respiration will be momentarily diminished through the fear created in the individual and this will show in the graph being drawn by the pen de. In this simple Way the device can be used as a lie detector.

at they end or the examination, the knobs si and @i are both swung into Oi position and this will stop the chart from moving and will also open the tubes 93, 94 and 95, so that the pens 68 and d8 will stop moving. The thumb screw 98a may now be rotated into open position and this will permit the air in the bag i @il and in the high pressure areas in the cylinder 9 to escape. The receptor F may now be removed and also the pressure bag E.

While I have shown only the preferred form of my invention, it should be understood that various changes or modirlcations may be made within the scope of the appended claims without departing from the spirit of the invention.

I claim:

1. In a device of the type described, a compartment having two opposing walls, a diaphragm secured to each wall and forming a high pressure, air conning space with each wall, means for delivering air under pressure to each space for inating the diaphragms, the centers of said diaphragms moving towards each other during inlation, said compartment having a low pressure region lying outside of the high pressure spaces, means for placing the low pressure region in communication with the atmosphere, said last-named means being closable for conning the air within t5 the low pressure region, and a diaphragm forming a part of the wall enclosing the low pressure region, said last-named diaphragm iiexing in accordance with variations in pressure in the high pressure regions when the low pressure region is closed to the atmosphere.

2. In a device of the type described, two high pressure regions separated from a low pressure region by two diaphragms, means for delivering air to the high pressure regions for moving the centers of the diaphragms toward each other, said low pressure region being confined by a wall, portions of which are formed by the two diaphragms, a third diaphragm also forming a part of the enclosure for the low pressure region and being exed in accordance with pressure changes in the high pressure regions.

3. A pressure reducing chamber comprising a cylindrical member, a plate covering each end of the member, a diaphragm placed between each plate and the member, means for clamping the plates to the member for sealing the edges of the diaphragms to the plates, means for delivering air under pressure into the spaces provided between the diaphragms and the plates, the centers of the diaphragms being moved toward each other during their inflation, and a third diaphragm forming a part of the cylindrical member, and being flexed in accordance with pressure changes in the spaces formed by the plates and the first two diaphragms.

4. In combination, a moving chart, a rockable shaft, a pen carried by the shaft and contacting with the chart, a cardiograph having a low pressure and two high pressure regions, a diaphragm constituting a part of the closure for the low pressure region, a link and arm operatively connecting the diaphragm with the shaft, two diaphragms separating the high pressure regions from the low pressure region, a tube communicating with the low pressure region and with the atmosphere, a tube for delivering air under pressure to each high pressure region, a. header connected to both of said last-named tubes, an air pressure gage connected with the header, pressure sensitive means communicating with the header, a bulb and tube for delivering air under pressure to the header, and means for closing said lastnamed tube and the tube communicating with the low pressure region.

5. In combination, a moving chart, a rockable shaft, a pen carried by the shaft and contacting with the chart, a cardiograph having a low pressure and two high pressure regions, a diaphragm constituting a part of the closure for the low pressure region, a link and arm operatively connecting the diaphragm with the shaft, two diaphragms separating the high pressure regions from the low pressure region, a tube communicating with the low pressure region and with the atmosphere, a tube for delivering air under pressure to each high pressure region. a header connected to both of said last-named tubes, an air pressure gage connected with the header, pressure sensitive means communicating with the header, a bulb and tube for delivering air under pressure to the header, and means for closing said last-named tube and the tube communicating with the low pressure region and a tension ring for varying the tension on the diaphragm-for the low pressure region.

6. In combination, a chart, means for movin-g the cha-rt at a predeterminedy speed, a cardiograph having two high pressure regions and a low pressure region, diaphragms separating the high pressure reg-ions from the low pressure region,

a diaphragm acted upon by the low pressure region, a pen operatively connected to the diaphragm and movable over the chart, a tube leading from the low pressure region to @the atmosphere, means for delivering air under pressure to the high pressure regions and including a Itube, a pressure gage and a pressure sensitive device in communication with the high pressure regions, a second pen movable over the chart, manually controlled means for causing the second pen to mark the chant in a predetermined manner, a pneumog-raph having a low pressure region, a. .third pen movable on the chart, a diaphragm acted upon by the low pressure region in the pneumograph and being operatively connected to the third pen, a tube placing the low pressure region in the pneuxnograph in communication with the atmosphere, a second pressure sensitive device communicating with tthe pneumog-raph, and a clamp for closing the tubes connected with the low pressure regions of :the cardiograph and pneumfog-raph and for also closing the tube connected with the high pressure air delivery means.

7. In a device of the device described, a high pressure region separated from a low pressure region by a diaphragm, means for delivering air to .the high pressure region for causing the diaphragm to fiex in accordance with changes in pressure in the high pressure region, a second diaphragm having no mechanical connection with lthe first diaphragm and forming a pant of the enclosure for the low pressure region and being flexed in accordance with pressure changes in the high pressure region, and a recording means by the second diaphragm.

8. In a device of the type described, a high pressure region separated from a low pressure region by -a diaphragm, said low pressure region communicating with the atmosphere, means for delivering air to the high pressure region for causing I'the diaphnagm to ilex in accordance with any changes in pressure in the high pressure region, a second diaphragm forming a part of the enclosure for the low pressure region, and means for closing off communication of the low pressure region with the atmosphere, whereby Ithe sec-ond diaphragm will ex in accordance with the pressure changes in the high pressure region.

9. In a device of the type described, a. high pressure region separated from a low pressure region by a. diaphragm, means for delivering air to the high pressure region to bring the air pressure up to the desired amount, means for varying the air pressure in the high pressure region in accordance with the pulse of an individual, means for venting the low pressure region to the atmosphere, an-d a recording means actuated by air pressure changes in the low pressure region, said venting means being closed for causing air pressure changes in Ithe high pressure region to aiiect similar air pressure changes in the low pressure region, whereby the recording means will indicate the changes in the high pressure region.

l0. In a sphygmograph having pressure transmitting means adapted to be applied to the body of a patient for transmitting variations in blood pressure and a recording devi-ce, an actuating means interposed between said inst-mentioned means and said recording device and including a high air pressure region and a low pressure region, a diaphragm separating Ithe two regions, the low pressure region normally opening to the atmosphere, said recording device being operated by changes of pressure in the low pressure region and being unaffected'by changes in the high pressure region so long as .the low pressure region remains open to the atmosphere, and means for closing oft the low pressure region from the atmosphere, whereby variations in pressure in the high pressure area will actuate the record-ing device.

11. In combination, a moving char-t, a pen movable over the chart, a cardiograph having a low pressure region and at least one high pressure region, a diaphragm constituting a part of the closure for the low pressure region, means operatively oonneoting the diaphragm with the pen for moving the pen in accordance wi-th the flexing of the diaphragm, at least one diaphragm separating ,the high pressure region from the low pressure region, said low pressure region being normally open to the atmosphere, means for delivering air under pressure to each high pressure region, a pressure sensi-tive means communicating with the high pressure region, and means for closing the communication of the low pressure reg-ion, with the atmosphere.

12. In combination, a chart, movable at a predetermined speed, a cardiogmaph having at least one high pressure region and a low pressure region, at least one diaphragm separating 'the high pressure region from fthe low pressure region, a diaphragm acted upon by the low pressure region, a pen operatively connected rto lthe last-named diaphragm and movable over the chart, said low pressure region being normally open to the atmosphere, means for delivering air under pressure .to .the high pressure region, an air inated mem-y ber communicating with the high pressure region and being sensitive to pressure changes, a second pen movable over the chant, manually controlled means for causing the second pen to mark the chart in a predetermined manner, a pneumograph having a low pressure region, a third pen movable on the chart, a diaphragm acted upon by the low pressure region in the pneumograph and being operatively connected to the third pen, the low pressure region in the pneumoraph being normally in communication with the atmosphere, a second pressure sensitive means communicating with the pneumognaph, and means for cutting off communication between the low pressure areas in the cardiograph and pneumograph, and the atmosphere.

CLARENCE D. LEE. 

